For clusters with accurately measured line-of-sight and proper motion velocity dispersion profiles one can determine cluster distances kinematically by varying the
cluster distance until the velocity dispersions are the same or a best match to a theoretical model of the cluster is achieved [1]}. The advantage of such kinematic distances is that, like parallaxes,
the kinematic distance method is a direct method which does not rely on other, more nearby methods in the distance ladder. Similar to parallax distances, kinematic distances
are also not affected by cluster reddening, allowing in principle to derive accurate distances for highly reddened clusters. In order to calculate kinematic distances, one either needs
to know the anisotropy profile of the internal velocity dispersion of a cluster, or assume that the cluster is isotropic. The latter is most often assumed since observed
velocity dispersion profiles usually show that globular clusters are isotropic, at least in their inner parts [2]}, [3]}, [4]}, [5]},
\(N\) -body simulations of star clusters also show that most globular clusters should have isotropic velocity dispersion profiles [6]}, [7]}, [8]}.
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